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J R Hickman

Publications and source records attributed to J R Hickman.

35 records · Page 2Linked to original sources
PubMed1984

Angiographic diagnosis of posterior mitral valve leaflet prolapse.

The left ventricular cineangiograms of 22 asymptomatic, apparently healthy male aviators without noninvasive (echocardiographic or auscultatory) evidence of mitral valve prolapse were reviewed and compared with those of 12 men with noninvasive evidence of mild mitral valve prolapse. The maximal protrusion of the posterior mitral valve leaflet superior and posterior to a line perpendicular to the long axis of the left ventricle at end-systole was measured from the right anterior oblique left ventricular cineangiogram by repeated observation of left ventricular inflow. The values were 7.5 +/- 1.6 mm in patients without mitral valve prolapse and 11.2 +/- 3.4 mm in patients with mitral valve prolapse (mean +/- 1 standard deviation). This measurement did not exceed 11 mm in any patient without prolapse. It is concluded that: 1) with meticulous attention to angiographic landmarks of the left ventricular inflow area, the limits of normal systolic posterior mitral leaflet motion can be defined; and 2) systolic motion outside these limits constitutes a quantitative criterion for the angiographic diagnosis of mitral valve prolapse.

Adult↗
PubMed1982

Limitations of the exercise stress test in the detection of coronary artery disease in apparently healthy men.

During a 1-year period, the United States Air Force School of Aerospace Medicine reviewed routine exercise tests by 771 completely asymptomatic male flying personnel aged 35-54 years, who underwent the stress test as the sole screening procedure to detect latent coronary artery disease. All of the aviators had a normal baseline 12-lead electrocardiogram, which would not have required a stress test in accordance with current policies of the USAF Central Electrocardiographic Library. Of these 771 exercise tests, 153 were maximal treadmill tests without a previous Double Master's Step test, and 618 were Double Master's tests. Borderline abnormal or abnormal Double Master's tests were followed by treadmill testing. Airmen with abnormal treadmill tests were offered coronary angiography for clarification of the aeromedical significance of the test result. The predictive value of a routine abnormal treadmill test in a population of aircrew members with a borderline abnormal or abnormal Double Master's test ranged from 17-55%. Thus, mass screening for coronary artery disease with exercise stress tests in apparently asymptomatic individuals is hampered by a low yield of true positive test in an unacceptably high proportion of false positive results.

Adult↗
PubMed1981

Computer-enhanced thallium scintigrams in asymptomatic men with abnormal exercise tests.

The use of treadmill testing in asymptomatic patients and those with an atypical chest pain syndrome is increasing, yet the proportion of false positive stress electrocardiograms increases as the prevalence of disease decreases. To determine the diagnostic accuracy of computer-enhanced thallium perfusion scintigraphy in this subgroup of patients, multigated thallium scans were obtained after peak exercise and 3 or 4 hours after exercise and the raw images enhanced by a computer before interpretations were made. The patient group consisted of 191 asymptomatic U.S. Air force aircrewmen who had an abnormal exercise electrocardiogram. Of these, 135 had normal coronary angiographic findings, 15 had subcritical coronary stenosis (less than 50 percent diameter narrowing) and 41 had significant coronary artery disease. Use of computer enhancement resulted in only four false positive and two false negative scintigrams. The small subgroup with subcritical coronary disease had equivocal results on thallium scintigraphy, 10 men having abnormal scans and 5 showing no defects. The clinical significance of such subcritical disease in unclear, but it can be detected with thallium scintigraphy. Thallium scintigrams that have been enhanced by readily available computer techniques are an accurate diagnostic tool even in asymptomatic patients with an easily interpretable abnormal maximal stress electrocardiogram. Thallium scans can be effectively used in counseling asymptomatic patients on the likelihood of their having coronary artery disease.

Adult↗
PubMed1981

Relation between high density lipoprotein cholesterol and coronary artery disease in asymptomatic men.

The well established inverse relation of high density lipoprotein cholesterol (HDL) and the risk of coronary artery disease was tested in a cross-sectional group of 572 asymptomatic aircrew members who were being screened for risk of coronary artery disease. A battery of tests was performed, including determinations of fasting serum cholesterol, HDL cholesterol and triglycerides and performance of a maximal symptom-limited exercise tolerance test. Of the 572 patients, 132 also had an abnormal S-T segment response to exercise testing or were otherwise believed to have an increased risk of organic heart disease and subsequently underwent coronary angiography. Significant coronary artery disease was found in 16 men and minimal or subcritical coronary disease in 14; coronary angiograms were normal in the remaining 102 men. The remaining 440 men, who were believed to have a 1 percent chance of having coronary artery disease by sequential testing of risk factors and treadmill testing, had a mean cholesterol level of 213 mg/100 ml, a mean HDL cholesterol of 51 mg/100 ml and a mean cholesterol/HDL ratio of 4.4. The mean values of cholesterol, HDL cholesterol and cholesterol/HDL cholesterol did not differ significantly in men with normal angiographic finding and those with subcritical coronary disease. However, 14 of 16 men with coronary artery disease had a cholesterol/HDL ratio of 6.0 or more whereas only 4 men with normal coronary arteries had a ratio of 6.0 or more. Of the classical coronary risk factors evaluated, the cholesterol/HDL ratio of 6.0 or more had the highest odds ratio (172:1). It appears that determination of HDL cholesterol level helps to identify asymptomatic persons with a greater risk of having coronary artery disease.

Adult↗
PubMed1980

Mitral valve prolapse--a review.

The past decade has seen a notable resurgence of interest in the systolic click-murmur syndrome. Previously regarded as extracardiac and benign, it is now clear that these auscultatory findings are central to a disorder characterized by abnormal systolic herniation (prolapse) of the mitral leaflets into the left atrium. Although it may be the result of diverse etiologies, the usual case represents an idiopathic, hereditary disorder of the valve leaflets with pathologic findings similar to those in Marfan's syndrome. The condition is very common and generally benign, and asymptomatic; however, a wide variety of clinical manifestations has been described, with a clinical picture at times indistinguishable from that of coronary artery disease. The small subset of patients at risk for malignant arrhythmias and sudden death has yet to be fully characterized. Although noninvasive techniques generally suffice for the diagnosis of MVP, left ventricular cineangiography is the definitive procedure. It remains for future studies in symptomatic and asymptomatic patients to define the relation between severity of MVP, its clinical manifestations, and its prognosis.

Adolescent↗
PubMed1980

Detection of coronary artery disease in asymptomatic aircrew members with thallium-201 scintigraphy.

Thallium-201 exercise myocardial perfusion scintigraphy was accomplished in 130 aircrew members prior to their undergoing coronary angiography. Most were undergoing cardiac catheterization for an abnormal exercise response to treadmill testing. Of these, 22 men had arteriographic evidence of obstructive coronary disease of at least 50% narrowing in a single vessel. All had abnormal myocardial scintigrams. There were 12 other aviators who had minimal degrees of coronary artery disease with lesions less than 50% as the maximum degree of obstruction. Of these, 8 had abnormal thallium scans showing a perfusion defect in the area of the myocardium, presumably supplied by the diseased coronary artery. Of the 96 men with normal angiograms, only 4 had abnormal myocardial scintigraphy. An abnormal myocardial scintigram was often associated with significant obstructive disease. A normal scan accurately ruled out the presence of high-grade obstructive lesions and missed only four cases of minimal coronary disease. The application of gated thallium myocardial perfusion scans in the practice of aerospace cardiology has important significant applications for followup of therapeutic modalities as well as screening for evidence of myocardial ischemia in apparently healthy aircrew members.

Adult↗
PubMed1980

Physical standards for high-performance fighter aircraft pilots.

The new generation of high-performance aircraft has clearly emphasized man's physiological limitations to withstand sustained high G loading. The selection and retention standards required to function in this environment have not been completely defined. The authors will offer a format of standards and screening tests, placing special emphasis on the detection of subclinical disease, particularly coronary artery disease. Cases which illustrate the spectrum of asymptomatic coronary disease will be presented. Other entities discussed will include conduction defects, mild valvular lesions, arrhythmias, and degenerative joint disease of the spine. An overall approach based on age, screening milestones, and specialized tests will be presented. Finally, a data repository on all pilots with chronic high G exposure will be discussed.

Adult↗
PubMed1979

Concurrent loss of consciousness and sino-atrial block during +Gz stress.

Current USAF fighter aircraft easily exceed human physiologic limits with their rapid onset of head-to-foot acceleration forces (+Gz). Sudden in-flight incapacitation caused by these increased +Gz forces could be disastrous with loss of materiel and human life. The physiologic mechanisms responsible for loss of consciousness (LOC) secondary to high +Gz must be fully understood so that maximum protection against it can be provided. An interesting case of an episode of LOC with concurrent sino-atrial block occurring during a relaxed rapid onset (1 G/s) centrifuge run is presented. The patient was undergoing flight medical evaluation for an episode of syncope, etiology unknown. An unusual characteristic of the patient was his high level of endurance training. The possibility of an excessive increase in vagal tone, developed by endurance training, is discussed as a probable etiology for this patient's prolonged time of incapacitation evidenced after +Gz-induced loss of consciousness.

Acceleration↗
PubMedDate not supplied

Abnormal hormone levels in men with coronary artery disease.

Plasma concentrations and urinary excretions of various hormones and hormone metabolites were measured in four groups. Group 1 was composed of 13 men with prior myocardial infarction; Group 2 contained 35 clinically normal men; Group 3 consisted of 44 men with normal coronary arteriograms; and Group 4 was composed of 25 men with severe coronary artery disease shown on arteriogram but no infarction. There were four major findings: Group 1 had significantly higher 24-hour mean plasma concentrations of estrone (E1), dehydroisoandrosterone (DHA), and dehydroisoandrosterone sulfate (DHAS) than Group 2, while Group 3 had the same levels as Group 4; Group 4 had significantly lower urinary excretion of androsterone glucuronide (AG) than Group 3, while Group 1 excreted normal amounts. There are three possible explanations for these findings: 1) myocardial infarction occurring in men with coronary artery disease may elevate the plasma levels of E1, DHA, and DHAS and eliminate the preinfarction depression of urinary AG levels; 2) higher than average levels of E1, DHA, DHAS, and AG may favor the development of infarction in men with coronary artery disease; 3) higher than average levels of E1, DHA, DHAS, and AG may favor survival from any infarction that occurs in men with coronary artery disease. Experimental and epidemiological evidence seems to favor the third possibility.

Adult↗